Concrete Calculator
Compute the cubic yards or metres of concrete for a slab, plus the number of 60-lb ready-mix bags. Perfect for footings, patios, walkways, and small slabs.
Your data never leaves your deviceFrequently Asked Questions
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How is concrete volume calculated?
Volume = length × width × thickness. Imperial uses ft × ft × (inches ÷ 12). Metric uses m × m × (cm ÷ 100). The result is converted into cubic yards (US) and cubic metres (metric).
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How many bags do I really need?
A 60-lb bag of ready-mix yields about 0.45 cu ft (0.013 m³). For pours larger than ~1 cu yd / 0.75 m³, ordering ready-mix delivery is usually cheaper than bags.
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Do I need extra rebar / mesh?
Slabs over 4 inches and footings benefit from rebar grids. The calculator only sizes concrete volume — reinforcement is a separate sizing problem.
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Privacy?
All math runs in your browser. No measurements are uploaded.